160 W. II. HAERIS ON MARINE MICROSCOPIC VEGETABLE ORGANISMS. 



Aclilya ceTvicornis. — A very minute and exceedingly graceful species ; 

 very sparingly branched. 



The filaments are furnished with appendages at regular intervals ; these 

 do not maintain the size at the apex they assume at the base, but taper to 

 quite fine points, in this respect differing from A. simplex and A. jforosa.), ■ 



Very rare. The only specimens obtained were found in material from 

 Challenger Stations 172 and 187, and from Java Sea^ Lagos Bay, and King 

 George's Sound, Australia, also from Barbadoes. 



]May be regarded as a shallow-water form. 



Achlya modosa. — This species appears to be closely allied to A. perforans, 

 the distinguishing feature being the frequent and nearly uniform expansion 

 of the filaments into nodular areas, whence arise lateral branches ; these 

 are developed at all angles, and retain the same feature. 



The appendages or excretory ducts are fairly numerous ; they consist of 

 short, rather stout, tubular processes arising from the median line of the 

 filaments. 



Not common, although widely distributed. Found at all depths down to 

 435 fathoms. Plate 10, Fig. 10 x 300. 



Achlya villom, var. quadvadiafa. — The filaments of this variety arc 

 generally rather robust, and are thickly clad with fine hair-like appendages : 

 they branch rather sparingly, the branches being produced at right angles, 

 sometimes singly, at others in pairs, in opposite directions ; they then form 

 a quadradiate figure. 



Achlya villosa is a very variable plant, even when selected from dredgings 

 procured from one locality : thus the filaments may be small or very rol^ust ; 

 sometimes they exhibit nodular expansions at irregular intervals ; or again, 

 they may be thickly clad with long appendages, or so sparingly furnished 

 and so short as almost to escape detection. 



Such variations naturally raise a doubt as to any useful purpose being 

 served by referring to the variety, and I should not have done so but for 

 the precedent set me by Mr. Waller in his paper on the Gabbard sands. I 

 aai disposed to regard the feature more as an accident of growth than of 

 specific value. 



Achlya aculeata. — This is a very elegant and minute species, occurring 

 singl}^ in shells, covering the surface with numerous very minute patches. 



The filaments have the appearance of being built up of innumerable short 

 club-shaped joints, each in turn giving rise to one or two similar growths : 

 the plants thus become a perfect network of short branches, which, 

 however, do not become confluent ; this part of the plant is rather deeply 

 embedded in the fragment, and each joint is very liberally furnished with 

 appendages ; these are sometimes simple, but frequently they are branched, 

 occasionally becoming divided into five or six terminal processes, which 

 reach the surface of the shell and give the organism a very bristly 

 appearance. 



The plants arise from flask-shaped cavities, which in their initial stage are 

 also provided with similar appendages. 



Very rare. Appears to be a coral-reef species, found in material from 

 Barbadoes, shallow water, 



